Japan's Emperor Akihito walks during a ritual called Taiirei Tojitsu Kashikodokoro Omae no Gi, a ceremony for the emperor to report the abdication ceremony to the goddess Amaterasu, at the Imperial Palace in Tokyo, Japan, on April 30, 2019. #

Crown Prince Akihito shakes hands with Air Force Captain L. Gordon Cooper, one of the seven American men being trained as astronauts, at Langley Field, Virginia, on September 29, 1960. Akihito was touring NASA's facilities. In the background are Koichiro Asakai (left), Japan's ambassador to the U.S., and Douglas MacArthur II, the U.S. ambassador to Japan. #

On November 12, 1990, Emperor Akihito leaves the throne in ancient court robes after his enthronement at the palace in Tokyo; 2,500 Japanese and foreign guests witnessed his proclamation of the official accession to the Chrysanthemum throne. #

Japan's Emperor Akihito waves and Empress Michiko smiles as they start an open-car parade from the palace on November 12, 1990, in Tokyo. The emperor formally ascended to the Chrysanthemum Throne earlier in the day. #

U.S. First Lady Barbara Bush and President George H. W. Bush stand at attention together with Japan's Emperor Akihito and Empress Michiko during a welcome ceremony at Tokyo's Guest House, on January 8, 1992. #

Emperor Akihito sows rice seeds in a seedbed at the Imperial Palace in Tokyo on April 14, 1997. The sowing was in preparation to plant the seedlings in a rice paddy at the palace the following month for harvesting in autumn and offering at the Ise Grand Shrine, as part of an imperial ritual. #

People walk over the Nijubashi bridge at the entrance of the Imperial Palace, which was opened for the New Year's public appearance by the Japanese royal family, in Tokyo, Japan, on January 2, 2014. #

Japan's Emperor Akihito and Empress Michiko pay their respects as they tour a damaged fishing port in Otsu, Kitaibaraki, about 70 kilometers south of the crippled Fukushima Daiichi Nuclear Power Station, on April 22, 2011, following the devastating March 11 earthquake and tsunami. #

Well-wishers cheer as Japan's Emperor Akihito appears with his family members on the balcony of the Imperial Palace to mark the emperor's 85th birthday in Tokyo on December 23, 2018. #

Japan's Emperor Akihito, flanked by Empress Michiko, Crown Prince Naruhito, Crown Princess Masako, Prince Akishino, Princess Kiko, Princess Mako, and Princess Kako wave to well-wishers on the emperor's 85th birthday at the Imperial Palace on December 23, 2018. #

Royal aficionado Fumiko Shirataki, 78, and her friend show each other photographs they took of Japan's Emperor Akihito and Empress Michiko, who passed in front of them at Kodomonokuni in Yokohama, Japan, on April 12, 2019. #

Japan's Emperor Akihito walks during a ritual called Taiirei Tojitsu Kashikodokoro Omae no Gi, a ceremony for the emperor to report the abdication ceremony to the goddess Amaterasu, at the Imperial Palace in Tokyo, Japan, on April 30, 2019. #

Japan's Emperor Akihito and Empress Michiko bow as they leave a ritual called Taiirei-Seiden-no-gi, a ceremony for the Emperor's abdication, in the Imperial Palace on April 30, 2019. #